This invention relates to new and useful improvements in offset pivot displacement-type guiding assemblies.
Displacement-type guiding assemblies are installed at intermediate guiding locations and used to control the lateral position of moving webs of material, such as paper, plastics, textiles and other flexible material being processed in continuous or roll form. These guiding assemblies are generally controlled by automatic control systems which employ a sensor that monitors the lateral web position immediately following the guiding assembly. As the web moves laterally at the sensor, a signal is generated which is transmitted to a servo mechanism which controls an actuator means connected to the guiding assembly. The guiding assembly provides continuous automatic lateral positioning of the moving web, thus closing the loop of the control system.
Displacement guides are used for guiding installations requiring excessive correction with minimum material spans entering and exiting the guide assembly. The entering and exiting web spans should be parallel to each other and perpendicular to the plane of guide motion.
It is desired that the positioning means be highly responsive to the driven power from the actuator whereby the web is quickly and accurately corrected in its path of movement into processing equipment. Such correction requires an adjustment of the positioning means, such as intermediate guides or unwinding and rewinding guiding assemblies. In order to accomplish such alignment, pivoted roller supporting frames have been used that have a drive connection with the actuator by pin connections, intermediate linkages, clevises, and other known connectors. This type of connector, however, has disadvantages in that it develops considerable friction and requires dimensional clearances. Such friction and dimensional clearances can cause lack of response and instability of the control system.
It is also desired that the positioning means be simplified in structure and operation, economical to manufacture and easy to maintain. Furthermore, it is desired that it be horizontally and vertically stable so as to provide a good support for the web passing over it. Such stability is also desired of course through the adjusting movement. Good support for the positioning means can be provided by large pivot bases or outboard supports, but this type of support adds undesirable friction drag to adjustable movement and of course also adds to the overall cost of the apparatus.